Editing Liquid crystal on silicon (section)

==Technology==
[[File:Hughes LCLV.svg|thumb|right|upright=1.5|Hughes LCLV schematic]]
The Hughes liquid crystal light valve (LCLV) was designed to modulate a high-intensity light beam using a weaker light source, conceptually similar to how an [[amplifier]] increases the amplitude of an electrical signal; LCLV was named after the common name for the [[triode]] [[vacuum tube]].<ref>{{cite journal |doi=10.1063/1.1654574 |title=AC Liquid-Crystal Light Valve |author1=Beard, T.D. |author2=Bleha, W.P. |author3=Wong, S-Y |date=1 February 1973 |volume=22 |issue=3 |journal=Applied Physics Letters|pages=90–92 |bibcode=1973ApPhL..22...90B }}</ref> A high-resolution, low-intensity light source (typically a [[cathode-ray tube|CRT]]) was used to "write" an image in the {{chem|Cd|S|link=Cadmium sulfide}} [[photosensor]] layer, which is energized by a transparent [[indium tin oxide]] electrode, driven by an alternating current source at approximately 10&nbsp;mV. A {{chem|Cd|Te|link=Cadmium telluride}} light-blocking layer prevents the low-intensity writing light from shining through the device; the photosensor and light-blocking layer together form a [[Rectifier|rectifying]] junction, producing a DC voltage bias across the [[liquid crystal]] layer, transferring the image to the reflecting side<ref>{{cite report |url=https://apps.dtic.mil/sti/citations/ADA060666 |title=Image Processing Applications of the Liquid Crystal Light Valve |author1=Smith, J. Lynn |publisher=Technology Laboratory, Redstone Arsenal |date=June 12, 1978 |access-date=16 January 2024}}</ref>{{rp|5}} by changing the rotation of [[Polarization (waves)|polarization]] in the [[twisted nematic]] liquid crystal. On the reflecting side, a high-intensity, polarized projection light source reflects selectively from the [[dielectric mirror]] based on the polarization within the liquid crystal being controlled by the photosensor. The dielectric mirror is formed by [[sputtering]] alternating layers of {{chem|Ti|O|2|link=Titanium dioxide}} and {{chem|Si|O|2|link=Silicon dioxide}}, with the final {{chem|Si|O|2}} layer etched to align the liquid crystal material.<ref>{{cite report |url=https://apps.dtic.mil/sti/citations/ADA039118 |title=Development of a Color Symbology AC Liquid Crystal Light Valve |author1=Jacobson, A.D. |author2=Bleha, W.P. |publisher=Hughes Research Labs |date=April 1977 |access-date=16 January 2024}}</ref>{{rp|10–12}} Later development of the LCLV used similar semiconductor materials arranged in the same basic structures.<ref>{{cite report |url=https://apps.dtic.mil/sti/citations/ADA123887 |title=Development of a Silicon Liquid-Crystal Light Valve for Multimode Operation |author1=Efron, U. |author2=Wiener-Avnear, E. |author3=Grinberg, J. |author4=Braatz, P.O. |author5=Little, M.J. |author6=Schwartz, R.N. |publisher=Hughes Research Labs |date=July 1982 |access-date=16 January 2024}}</ref>{{rp|10}}

[[File:JVC D-ILA.svg|thumb|left|upright=1.5|Hughes-JVC D-ILA schematic]]
The LCLV principle is carried forward in a digital LCoS display device, which features an array of [[pixel]]s, each equivalent to the reflecting side of a single LCLV. These pixels on the LCoS device are driven directly by signals to modulate the intensity of reflected light, rather than a low intensity "writing light" source in the LCLV. For example, a chip with XGA resolution has an array of 1024×768 pixels, each with an independently addressable transistor.<ref>{{cite web |url=http://pro.jvc.com/pro/hjt/technology/download/dilaguide.pdf |title=D-ILA: The Technology for images of perfection |publisher=JVC |date=June 2000 |access-date=16 January 2024}}</ref> In the LCoS device, a [[complementary metal–oxide–semiconductor]] (CMOS) chip controls the voltage on square reflective aluminium electrodes buried just below the chip surface, each controlling one pixel. Typical chips are approximately {{cvt|1–3|cm}} square and approximately {{cvt|2|mm}} thick, with [[pixel pitch]] as small as {{cvt|2.79|μm|mil}}.<ref>{{cite web|author=Compound Photonics |title=Products Compound Photonics |url=http://www.compoundphotonics.com/products/light-engines |access-date=2014-10-13 |url-status=dead |archive-url=https://web.archive.org/web/20141018065638/http://www.compoundphotonics.com/products/light-engines |archive-date=October 18, 2014 }}</ref> A common voltage for all the pixels is supplied by a transparent conductive layer made of indium tin oxide on the cover glass.